Nordic is a Gtk3.20+ theme based on the fantastic Nordic.
Fork of Nordic with the palette shifted towards darker and slightly more saturated and luminous colors. Floating Gnome top panel.
Extract the zip file to the themes directory i.e. /usr/share/themes/ or ~/.themes/ (create it if necessary).
To set the theme on Gnome, run the following commands in Terminal:
gsettings set org.gnome.desktop.interface gtk-theme "Reverie"
gsettings set org.gnome.desktop.wm.preferences theme "Reverie"
or Change via distribution specific tool.
This theme is not actively maintained. YMMV.